Effect of intestinal ischemia-reperfusion injury on protein levels of leptin and orexin-A in peripheral blood and central secretory tissues

Leptin administration alleviates ischemic brain injury in mice by reducing oxidative stress and subsequent neuronal apoptosis

BACKGROUND

Recent research has indicates that leptin plays a protective role in traumatic brain injury. We studied the protective effect of leptin on cerebral ischemia/reperfusion injury by using mice transient focal cerebral ischemia/reperfusion injury model.

METHODS

The distribution of 125I-leptin in the mouse brain was assessed by radioimmunoassay method. Mouse models of transient focal cerebral ischemia were established by occlusion of the right middle cerebral artery for two hours followed by 24 hours reperfusion. The neurologic deficits and infarct volume were determined using the Longa's score and 2,3,5-triphenyltetrazolium chloride staining, respectively. Regional cerebral blood flow was monitored by a laser-Doppler blood flowmeter. The levels of malondialdehyde, nitric oxide, nitric oxide synthase, and superoxide dismutase were detected according to respective assay kit. The histologic changes and neuronal apoptosis were observed with hematoxylin and eosin and transferase-mediated dUTP-biotin nick end labeling staining, respectively. The expression of B-cell lymphoma/leukemia-2 (Bcl-2) and cysteineasparateprotease-3 (caspase-3) were investigated by Western blot and real-time polymerase chain reaction assay.

RESULTS

Leptin decreased infarct volume and neurologic defects and improved regional cerebral blood flow and microvascular branch blood flow after injury. The malondialdehyde and nitric oxide levels were reduced, and superoxide dismutase level was increased after leptin treatment, which also minimized histologic changes and neuronal apoptosis, led to the upregulation of Bcl-2 and downregulation of caspase-3 expression after injury.

CONCLUSIONS

Peripherally administered leptin crossed the blood-brain barrier and was distributed into multiple regions of the brain; in the brain, leptin directly alleviated the injury-evoked damages by reducing oxidative stress and neuronal apoptosis.

Unraveling the link between leptin, ghrelin and different types of colitis

Leptin and ghrelin are hormones with a tight inverse functional connection. Their inverse association is observed not only in the modulation of metabolism but also in the interaction with the immune system. A large number of studies have been launched regarding their association with various disorders, including different types of colitis. The majority of the available literature, however, focuses on inflammatory bowel disease. The role of leptin and ghrelin appears to be aggravating in most of these studies. Concerning intestinal infections, their levels seem to depend on the presence of certain species of micro-biota. As for models of ischemic and miscellaneous colitis, both hormones seem to act protectively, although evidence deriving from human studies is needed before any safe conclusions can be made. Conclusively, it seems that available data, from in vitro, animal and human studies, suggest of a multifarious role for leptin and ghrelin, in the face of different triggers, which in turn cause diverse types of colitis. Bearing this in mind, gaps and loose ends are detected in the associated literature to encourage further research through which the association of leptin and ghrelin with intestinal inflammation could be clarified and expanded so that other types of colitis could also be included.

Endogenous leptin fluctuates in hepatic ischemia/reperfusion injury and represents a potential therapeutic target

AIM: To evaluate the role of leptin in the internal disorders during hepatic ischemia/reperfusion injury.

METHODS: A rat model of 70% hepatic ischemia/reperfusion injury was established, with groups of sham-operation (Sham), 60 min ischemia/60 min reperfusion (I60’R60’), I60’R150’, I60’R240’ and I60’R360’. Serum leptin was detected by a self-produced radioimmunoassay; serum glucose, total anti-oxidation capacity, myeloperoxidase, alanine transaminase and diamine oxidase were determined by relevant kits, while histological alterations and protein levels of leptin in the lung, liver and duodenum were examined by hematoxylin-eosin staining and immunohistochemistry. Spearman’s rank correlation between leptin and other variables or grading of tissue impairment were analyzed simultaneously.

RESULTS: Serum leptin in I60’R360’ was significantly higher than in Sham and I60’R240’ groups (both P < 0.05), serum glucose in I60’R360’ was higher than in Sham and I60’R150’ (both P < 0.05), and serum total anti-oxidation capacity in I60’R240’ and I60’R360’ were higher than in Sham (both P < 0.05) and I60’R150’groups (both P < 0.01). Serum myeloperoxidase in groups of I60’R240’ and I60’R360’ were lower than in I60’R150’group (both P < 0.05), serum alanine transaminase in the four reperfusion groups were higher than in the Sham group (all P < 0.05), while serum DAO in I60’R360’ was lower than in I60’R60’ (P < 0.05). Histological impairment in the lung, liver and duodenum at the early phase of this injury was more serious, but the impairment at the later phase was lessened gradually. Protein levels of leptin in the lung in the four reperfusion groups were significantly lower than in the Sham group (all P < 0.01), decreasing in the order of I60’R150’, I60’R60’, I60’R360’ and I60’R240’; the levels in the liver in I60’R60’ and I60’R240’ were higher than in the Sham group (both P < 0.01), while the levels in I60’R240’ and I60’R360’ were lower than in I60’R60’ (both P < 0.01); the levels in duodenum in I60’R240’ and I60’R360’ were higher than in Sham, I60’R60’ and I60’R150’ (all P < 0.01), while the level in I60’R150’ was lower than in I60’R60’ (P < 0.05). There was a significantly positive correlation between serum leptin and alanine transaminase (ρ = 0.344, P = 0.021), a significantly negative correlation between the protein level of leptin in the lung and its damage scores (ρ = -0.313, P = 0.036), and a significantly positive correlation between the protein level of leptin in the liver and its damage scores (ρ = 0.297, P = 0.047).

CONCLUSION: Endogenous leptin fluctuates in hepatic ischemia/reperfusion injury, exerts a potency to rehabilitate the internal disorders and represents a potential target for supportive therapy.

Heart-type fatty acid-binding protein is a useful marker for organ dysfunction and leptin alleviates sepsis-induced organ injuries by restraining its tissue levels

Heart-type fatty acid-binding protein (H-FABP) is widely distributed and has been used to diagnose certain diseases. However, its alteration during infection-evoked organ dysfunction, and the potential association between leptin and it in injury or infection has not been investigated. In the current study, serum H-FABP, leptin, C-reactive protein and interleukin-1beta in the patients with pulmonary infection-induced multiple organ dysfunction were detected. Moreover, a mouse model of sepsis was established, and serum alanine transaminase, uric acid, tissue H-FABP, myeloperoxidase, superoxide dismutase activity and histological alterations in lung and intestine were investigated. Serum H-FABP and leptin increased simultaneously and significantly in the patients, and leptin alleviated pulmonary and intestinal injuries by restraining tissue H-FABP secretions in the mouse model of sepsis. Other investigated variables showed different but independent alterations. In conclusion, H-FABP represents a useful diagnostic marker for organ dysfunction, and its association with leptin will be a novel target for emergency aid.

The effect of leptin on intestinal recovery following ischemia-reperfusion injury in a rat

Recent evidence suggests that the adipose tissue derived cytokine leptin (LEP) is involved in the modulation of growth and differentiation of normal small intestine. The purpose of the present study was to examine the effect of leptin on enterocyte turnover and intestinal recovery after ischemia-reperfusion (IR) injury in a rat. Male Sprague-Dawley rats were divided into three experimental groups: (1) sham rats underwent laparotomy, (2) IR-rats underwent occlusion of both superior mesenteric artery and portal vein for 30 min followed by 24 h of reperfusion, and (3) IR-LEP rats underwent IR and were treated with leptin given subcutaneously at a dose of 50 microg/kg once a day for 48 h before and 24 h following IR. Intestinal structural changes, enterocyte proliferation and enterocyte apoptosis were determined 24 h following IR. A non-parametric Kruskal-Wallis ANOVA test was used for statistical analysis with P < 0.05 considered statistically significant. Treatment with leptin resulted in a significant increase in bowel weight in ileum, mucosal weight in jejunum and ileum, mucosal DNA content in ileum, mucosal protein content in jejunum and ileum, villus height in jejunum and ileum, and crypt depth in jejunum compared to IR-animals. IR-LEP rats also had a significantly lower intestinal injury score as well as lower apoptotic index and higher cell proliferation index in jejunum and ileum compared to the IR-animals. In conclusion, pre-treatment with leptin prevents gut mucosal damage and improves intestinal rehabilitation following intestinal IR in a rat.

Circulating Cytokines, Chemokines, and Stress Hormones are Increased in Patients with Organ Dysfunction Following Liver Resection

BACKGROUND

Humoral mediators are potentially involved in the pathogenesis of postoperative complications following surgery. The aim of the present study is to evaluate the postoperative responses of circulating cytokines, chemokines, and stress hormones following liver resection, and their effects on postoperative infectious complications and organ dysfunction.

PATIENTS AND METHODS

Perioperative plasma concentrations of interleukin (IL)-6, IL-10, IL-4, IL-8, macrophage chemoattractant protein (MCP)-1, cortisol, macrophage migration inhibitory factor (MIF), and leptin were measured by immunoassays in 128 consecutive patients undergoing liver resection.

RESULTS

Forty-three patients had postoperative infection and 11 had infection-related organ dysfunction. Plasma levels of all mediators except for IL-4 increased postoperatively. Postoperative levels of IL-6, IL-10, IL-8, MCP-1, cortisol, and leptin were significantly higher in patients with organ dysfunction than in those without organ dysfunction (P < 0.05). However, postoperative MIF levels were not affected by postoperative infection or organ dysfunction. Plasma levels of IL-6, IL-10, IL-8, and MCP-1 were positively correlated with operation time (P < 0.0001) or blood loss (P < 0.0001), and higher in patients with jaundiced liver (P < 0.05). In univariate logistic regression analyses, elevated IL-6, IL-10, IL-8, and MCP-1, advanced age, large volume of blood loss, long operation time, long hepatic ischemia time, and major liver resection were significantly correlated with postoperative infection (P < 0.05). In multivariate analyses, IL-6 and IL-10 were significant predisposing factors for postoperative infection (P < 0.05), and blood loss and IL-6 for organ dysfunction (P < 0.01).

CONCLUSIONS

These results suggest that IL-6, IL-10, IL-8, MCP-1, cortisol, and leptin are released after liver resection in response to surgical stress and correlated with postoperative infection and organ dysfunction, and that of these circulating mediators, IL-6 and IL-10, have a close relationship to the complications.

Protective effect of leptin against ischemia-reperfusion injury in the rat small intestine

BACKGROUND

The small intestine is extremely sensitive to ischemia-reperfusion (I/R) injury and a range of microcirculatory disturbances which contribute to tissue damage. Previous studies have shown that leptin plays an important physiological role in the microvasculature. The aim of this study was to evaluate the protective effects of leptin in I/R--induced mucosal injury in the small intestine.

METHODS

Forty rats were divided into 5 groups (n = 8). Group I was subjected to a sham operation. Following mesenteric ischemia in group II (control); physiologic saline 1 cm3, in group III; leptin 100 microg/kg, and physiologic saline 1 cm3, in group IV; NG-L-arginine methyl ester (L-NAME) 20 mg/kg, and physiologic saline 1 cm3, in group V; leptin 100 microg/kg, L-NAME 20 mg/kg, and physiologic saline 1 cm3 were given intra-peritoneally. In these groups, an I/R procedure was performed by occlusion of the superior mesenteric artery for 45 min followed by 120 min reperfusion. After reperfusion, the small intestines were resected for malondialdehyde (MDA) and nitric oxide (NO) concentration and histopathologic properties. Mucosal lesions were scored between 0 and 5. Tissue MDA and NO concentration and histopathologic grades were compared statistically.

RESULTS

Tissue MDA level significantly increased (P < 0.05), tissue NO level significantly decreased in group V animals, compared to group III animals respectively (P < 0.001). Histopathologically, intestinal injury significantly decreased in the leptin treated ischemic group.

CONCLUSION

Leptin can be used safely in mesenteric occlusive diseases, since it induces NO formation and release in mesenteric vessels.